RESUME The information content of ENVISAT ASAR alternating polarization data is evaluated with respect to operations at the Canadian Ice Service. A dual polarization data set covering an entire ice season is shown to have a higher information content compared to single polarization data. Automatic sea ice classification with dual polarization data is shown to have some potential to aid operatio...

Our study examined the consequences of the economic reform programme on poverty and survival strategies in Ethiopia since 1989, with an emphasis on the rural economy. We used a very detailed household panel data set covering about 1450 households in 15 villages in rural Ethiopia, supplemented with some primary and secondary sociological and anthropological data. The emphasis has been on disenta...

A collection of landmarks is complete if the cost of a minimum-cost hitting set equals h and there is a minimumcost hitting set that is an optimal relaxed plan. We present an algorithm for generating a complete collection of landmarks and we show that this algorithm can be extended into effective polytime heuristics for optimal and satisficing planning. The new admissible heuristics are compare...

Minimal explanations of infeasibility are of great interest in many domains. In propositional logic, these are referred to as Minimal Unsatisfiable Subsets (MUSes). An unsatisfiable formula can have multiple MUSes, some of which provide more insights than others. Different criteria can be considered in order to identify a good minimal explanation. Among these, the size of an MUS is arguably one...

1Pontificia Universidad Católica de Valparaı́so, 2362807 Valparaı́so, Chile 2Universidad San Sebastián, 8420524 Santiago, Chile 3Universidad Central de Chile, 8370178 Santiago, Chile 4Universidad Autónoma de Chile, 7500138 Santiago, Chile 5Universidad Cientifica del Sur, Lima 18 Lima, Peru 6Universidad de Playa Ancha, 2360003 Valparaı́so, Chile 7Escuela de Ingenieŕıa Industrial, Universidad Diego ...

The multiple weighted hitting set problem is to find a subset of nodes in a hypergraph that hits every hyperedge in at least m nodes. We extend the problem to a notion of hypergraphs with so-called hypernodes and show that, for m = 2, it remains fixed-parameter tractable (FPT), parameterized by the number of hyperedges. This is accomplished by a nontrivial extension of the dynamic programming a...

In the double TSP with multiple stacks, a vehicle with several stacks performs a Hamiltonian circuit to pick up some items and stores them in its stacks. It then delivers every item by performing another Hamiltonian circuit while satisfying the last-in-first-out policy of its stacks. The consistency requirement ensuring that the pickup and delivery circuits can be performed by the vehicle is th...

In this paper we consider set covering problems with a coefficient matrix almost having the consecutive ones property, i.e., in many rows of the coefficient matrix, the ones appear consecutively. If this property holds for all rows it is well known that the set covering problem can be solved efficiently. For our case of almost consecutive ones we present a reformulation exploiting the consecuti...

This paper reviews the recent development of the formal framework of priority algorithms for scheduling problems [BNR02]; the extension of the model for facility location and set cover [AB02], and graph problems [DI02]. We pose some open questions and directions for future research.